Apparatus for copying different size documents in a copying machine

ABSTRACT

Apparatus for driving the illumination exposure system of a copying machine where the illumination exposure system includes means for scanning a stationary document in a first direction and means for returning the scanning means in the opposite direction to a start position after scanning has been completed, the apparatus comprising variable, cyclic timing means for determining (1) a first timing cycle required for the scanning means to scan a first sized document and for the scanning means to be returned to its start position and (2) a second timing cycle required for the scanning means to scan a second sized document smaller than the first sized document and for the scanning means to be returned to its start position, the timing means being responsive to a control signal for initiating each timing cycle to thereby initiate scanning by the scanning means and the timing means being non-responsive to further control signals until each timing cycle is complete; driving means responsive to the timing means for driving the scanning means to scan the stationary document; settable control means for controlling the length of time the driving means is responsive to the timing means so that (1) with a first setting of the settable control means the scanning means scans substantially only the length of the first sized document and is then returned to its starting position and (2) with a second setting thereof the scanning means scans substantially only the length of the second sized document and then is returned to its starting position; second control means responsive to the second setting of the settable control means, the second control means being actuated when scanning of the second sized document is complete to decrease the time it takes for the timing means to complete its timing cycle so that the timing cycle for the second sized document is shorter than that for the first sized document whereby the number of second sized documents that may be copied per unit time is less than that of the larger, first sized documents.

United States Patent 1 Namba 1 July 15,1975

[ APPARATUS FOR COPYING DIFFERENT SIZE DOCUMENTS IN A COPYING MACHINE [75] Inventor: Yoshiharu Namba, Tokyo, Japan [73] Assignee: Fuji Xerox Co., Ltd., Tokyo, Japan [22] Filed: Jan. 17, 1974 21 Appl. No.: 434,183

[30] Foreign Application Priority Data Jan. 27, 1973 Japan 48-10690 [52] U.S. Cl. 355/66; 355/8; 355/47 [51] Int. Cl. G03b 27/70; 603g 15/04 [58] Field of Search 355/8, 14, 47-51, 355/66 [56] References Cited UNITED STATES PATENTS 3,062,095 ll/l962 Rutkus et al 355/8 3,554,640 l/l97l Hoskins 355/8 Primary ExaminerSamuel S. Matthews Assistant ExaminerKenneth C. Hutchison Attorney, Agent, or FirmGerald J. Ferguson, Jr.; Joseph J. Baker [57] ABSTRACT Apparatus for driving the illumination exposure system of a copying machine where the illumination exposure system includes means for scanning a stationary document in a first direction and means for returning the scanning means in the opposite direction to a start position after scanning has been completed, the

apparatus comprising variable, cyclic timing means for determining (l) a first timing cycle required for the scanning means to scan a first sized document and for the scanning means to be returned to its start position and (2) a second timing cycle required for the scanning means to scan a second sized document smaller than the first sized document and for the scanning means to be returned to its start position, the timing.

means being responsive to a control signal for initiating each timing cycle to thereby initiate scanning by the scanning means and the timing means being nonresponsive to further control signals until each timing cycle is complete; driving means responsive to the timing means for driving the scanning means to scan the stationary document; settable control means for controlling the length of time the driving means is responsive to the timing means so that (1) with a first setting of the settable control means the scanning means scans substantially only the length of the first sized document and is then returned to its starting position and (2) with a second setting thereof the scanning means scans substantially only the length of the second sized document and then is returned to its starting position; second control means responsive to the second setting of the settable control means, the second control means being actuated when scanning of the second sized document is complete to decrease the time it takes for the timing means to complete its timing cycle so that the timing cycle for the second sized document is shorter than that for the first sized document whereby the number of second sized documents that may be copied per unit time is less than that of the larger, first sized documents.

7 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to apparatus for use in copying machines which can copy manuscripts of different sizes, such as A 4, B4, etc.

2. Discussion of the Prior Art With conventional copying machines, for example, with copying machines designed for copying manuscripts of B 4 size, it is often desirable to make copies of smaller A 4 sized manuscripts. However, the area scanned remains the same for both sized documents including the useless difference in area between B 4 and A 4 manuscripts. Hence even when making A 4 sized copies, the number of copies made per unit time is equal to the number of B 4 sized copies made per unit time in these prior art copying machines.

SUMMARY OF THE INVENTION It is thus a primary object of this invention to provide an apparatus which, when the manuscript to be copied is small in size, the area corresponding to the difference between the smaller manuscript and a larger one is not scanned thereby shortening the time until the next scan can commence so that the number of copies made per unit time for the smaller sized manuscripts can be increased with respect to the larger sized ones.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of an illustrative copying machine in which the apparatus of this invention is useful.

FIG. 2 is a perspective view of an illustrative illumination exposure system for use in this invention.

FIG. 3 is a perspective view of an illustrative embodiment of this invention which comprises apparatus for actuating the illumination exposure system of FIG. 2.

- FIG. 4 is a cross-sectional view of an illustrative spring clutch for use with this invention.

FIG. 5 is a perspective schematic diagram of an illustrative driving mechanism for a driving gear of FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 is a schematic diagram of an illustrative copying machine in which the apparatus of this invention is useful. An illumination exposure system 1, a magnetic brush developer 2, a blade cleaner 3, a fuser 4, a toner dispenser 5, a pivot cassette tray 6, a paper transport 7, a power supply 8, a charging corotron 9, a pretransfer corotron 10, a transfer corotron 11, a further corotron 12, a preclean corotron 13, a feeder roll 14, and a snap gate are shown and conventionally utilized.

The above-mentioned illumination exposure system 1 is conventional and may be as shown in FIG. 2 where carriages l6 and 19, a lamp l7, mirrors 18, 19a, and 20, and lens mirror 21 are shown. Mirror carriages 16 and 19 scan a stationary document reciprocatively in response to rotation of scanning shaft 22 via pulley 23 and wire 24. A return spring 22a is provided to return carriage l6 and 19 to start position after each scan is completed.

The apparatus of this invention which drives scanning shaft 22 may be as shown in FIG. 3 where'a driving gear 25, an input gear 26 engaged with driving gear 25,

and a main shaft 27 positioned at the core of the input gear 26 are shown. A spring clutch 28 selectively links input gear 26 with main shaft 27 to rotate the shaft in one direction only.

Spring clutch 28 does not transmit rotation to shaft 27 unless solenoid 34, connected thereto, is excited.

Solenoid 34 may be excited by an electrical signal such as an electrical pulse and when it is excited, its magnet bar is withdrawn into the core of the solenoid whereupon a pawl 33 connected to the bar is withdrawn from a lobe 31a provided on spring clutch 28.

Lobe 31a has no hitch or catch on its back side so that with one excitation of solenoid 34, the spring clutch 28 turns 360 until it is stopped by the release pawl 33. In other words, the spring clutch 28 can transmit rotation to shaft 27 only when pawl 33 is not holding lobe 31a.

Spring clutch 28 may comprise, as shown in FIGS. 3 and 4, an output side sleeve 30 secured to main shaft 27, the input gear 26 being rotatably engaged with sleeve 30. A stop collar 31, from the periphery of which protrudes allobe 31a, encircles bosses 26a and 30a of gear 26 and sleeve 30, respectively, as shown in FIG. 4. A wrap spring 32, one end of which is attached to the output side sleeve 30 and the other end of which loosely touches stop collar 31, is interposed between the aforementioned boss and stop collar 31. Wrap spring 32 is wound in a direction opposite to the rotation of input gear 26. Thus, when lobe 31a is engaged by pawl 33 to wrap spring 32 is loosened to disconnect the input gear 26 from the output side sleeve 30 (off state). If pawl 33 is released from lobe 31a, the spring, due to rotation of input gear 26, is tightened so that its diameter is narrowed thereby bringing input gear 26 into engagement with the boss of the output side sleeve 30 (on state).

Referring to FIG. 3, input gear 26 engages, via an idler gear 35, a gear 37 fastened to a counter shaft 36. An electromagnetic clutch 38 is provided on counter shaft 36. On the output side of clutch 38 is fastened a gear 39. The gear 39 via an idler gear 40 engages a gear 41 fastened to main shaft 27. The gear ratio of the gear 39 to the gear 41 is such as to increase the speed of the main shaft 27 driven by driving gear 25 and input gear 26, by a determined number of revolutions per unit time. A collar 42 is attached to main shaft 27. A pulley 43 is rotatably fitted to main shaft 27 adjacent to collar 42. A wire or belt 45 is run between pulley 43 and the pulley 44 fastened to the scanning shaft 22 of the illumination exposure system 1, see FIG. 2. The scanning shaft 22 is rotated as pulley 43 on main shaft 27 is rotated. On the periphery of collar 42 is provided a notch 46. A pawl member 47 releasably engages notch 46. Pawl 47 is provided on pulley 43 in such a manner that the pawl is released upon contact with a release lever 48, the fixed position of which can be varied depending on the size of the manuscript being copied. Because of collar 42 and pawl member 47, the rotation of main shaft 27 can be intermittently transmitted to pulley 43.

Drive gear 25, on the other hand, is driven by a motor 50 through a chain 49 run through a plurality of idler pulleys, as shown in FIG. 5.

In operation, torque transmission by the above described apparatus is as described below. First when the system is in a non-scanning mode, spring clutch 28 and electromagnetic clutch 38 are off. Under this condition, the counter shaft 36 will be rotated via driving gear 25, input gear 26, idler gear 35 and gear 37. The electromagnetic clutch 38 at this time is off. Hence counter shaft 36 runs idle with respect to gear 39. Also since solenoid 34 has not be energized, spring clutch 28 does not transmit the rotational force of input gear 26 to main shaft 27. Hence, main shaft 27 is not rotated and no rotational force is transmitted to scanning shaft 22.

Next, when the scanning is intended, solenoid 34 is energized to turn on spring clutch 28, electromagnetic clutch 38 being turned off at this time. The rotation of the input gear 26, driven by the drive gear 25, is transmitted to main shaft 27 via spring clutch 28. The rotation of main shaft 27 is transmitted to scanning shaft 22 through collar 42, pawl 47, pulley 43, wire or belt 45 and pulley 44. As scanning shaft 22 rotates, carriage 16 moves to perform scanning. Gear 39 of counter shaft 36 also rotates due to the rotation of main shaft 27. But since electromagnetic clutch 38 is in the off state, gear 39 runs idle.

When the scanning is finished, pawl 47 contacts release lever 48 to disengage collar 42 of main shaft 27 from pawl 47. Carriages 16 and 19 are then returned to the start position by return spring 22a.

When a manuscript of B 4 size is scanned, release lever 48, which is set at a position of 32503' after the start of scanning, causes collar 42 to disengage from pawl 47. While carriages l6 and 19 are being returned to the start position, the output side of spring clutch 28 continues its rotation until it has rotated once that is, 360at which time the output side of spring clutch 28 is hooked at lobe 31a and stops. At this time, return of carriages 16 and 19 to the start position has just been completed.

When a manuscript of A 4, size smaller than the above-mentioned B 4 size, is being copied, the process until scanning is complete is the same as that for B 4 sized manuscripts. However, when scanning the A 4 sized manuscript, the position of the release lever 48 is moved as shown by 48 in FIG. 3, so that engagement of pawl 47 with collar 42 is released at an angle of 2715l' after scanning has started. Thus, when the scanning of the A 4 sized manuscript is complete that is, when pawl 47 is disengaged from collar 42 and carriages l6 and 19 are returned to the start position electromagnetic clutch 38 is turned on and then turned off before the output side of spring clutch 28 reaches 360. Although not shown for purpose of clarity, this may be simply effected by positioning a microswitch to respond to the release of pawl 47 from collar 42 to thereby generate a trigger pulse for actuating a single shot multivibrator, the output pulse of which is applied to clutch 38..The pulse width may be appropriately controlled to insure that clutch 38 is turned off before the output side of spring clutch 28 reaches 360. Due to the actuation of clutch 38, the rotation of counter shaft 36 is transmitted to gear 39 viaelectromagnetic clutch 38 and then transmitted to main shaft 27 via gear 39. The number of revolutions per unit time transmitted from counter shaft 36 is higher by a predetermined number than the number of revolutions per unit time transmitted from driving gear 25 through input gear 26 and spring clutch 28. Hence, the number of revolutions per unit time on the output side of spring clutch 28 starts to correspondingly increase simultaneously with completion of scanning of the A 4 sized manuscript.

That is,the output side of spring clutch 28, when scanning is completeof a B 4 sized paper, is at a position 32503 from the start of scanning, as mentioned above; whereas the output side of spring clutch 28, when scanning is complete of a A 4 sized paper, will be at a position of 27151' from the starting position. Due to the increased speed of main shaft 27, the output side of spring clutch 28 is accelerated to the 360 position; the time required for the rotation from 2715l' to 360 when copying A 4 sized paper is typically nearly equal to the time required for the rotation from 32503' to 360 when copying B 4 sized paper. Therefore, the time per cycle when copying A 4 size paper is shorter than the time per cycle when copying B 4 sized paper, and the number of A 4 size papers copied per unit time will be greater than the number of B 4 size papers copied per unit time. The difference between the rotation of input gear 26, driven by driving gear 25, and the rotataion of main shaft 27, which rotates faster than the input gear 26, is absorbed by the one-way action of spring clutch 28.

After the above-mentioned angle advancing operation has finished, spring clutch 28 is turned off and assumes stand-by for the next scanning operation. Although not shown for purpose of clarity, appropriate means (such as a bias spring connected between pawl 47 and pulley 43) for again engaging pawl 47 with co]- lar 42 at the end of the timing cycle of spring clutch 28 are provided. I

In summary, according to this invention, an amplification means containing a clutch 38 which is normally off is interposed between the input side and the output side of the spring clutch 28, and clutch 38 is so connected as to accelerate the rotation of the output side of spring clutch 28 relative to the input side thereof. Accordingly, in copying machines employing the apparatus of this invention, where a manuscript or paper of a smaller size is being copied, the revolving speed on the output side of spring clutch 28 can be increased during the time when scanning of a larger manuscript would continue and thus time before the next scan may start is reduced. This, of course, increases the number of copies that may be made per unit time for those manuscripts or papers of smaller sizes thus contributing to increased copying efficiency.

Numerous modifications of the invention will become apparent to one of ordinary skill in the art upon reading the foregoing disclosure. During such a reading, it will be evident that this invention provides a unique apparatus for copying different sized documents in a copying machine.

What is claimed is:

1. Apparatus for driving the illumination exposure system of a copying machine where the illumination exposure system includes means for scanning a stationary document in a first direction and means for returning the scanning means in the opposite direction to a start position after scanning has been completed, said apparatus comprising:

variable, cyclic timing means for determining (l) a first timing cycle required for said scanning means to scan a first sized document and for said scanning means to be returned to its start position and (2) a second timing cycle required for said scanning means to scan a second sized document smaller than said first sized document and for said scanning means to be returned to its start position, said timing means being responsive to a control signal for initiating each timing cycle to thereby initiate scanning by said scanning means and said timing means being nonresponsive to further control signals'until each timing cycle is complete, said variable'cyclic timing means comprising (a) a spring cutch, the input side of which is connected to a source of rotative power and the output side of which is removably connected to said driving means via said main shaft, and (b) a first control source for actuating said spring clutch to connect the input and output sides thereof, said spring clutch including means for disconnecting said input and output sides thereof after said output side has been rotated through a p'redetermined angle;

driving means mounted on a main shaft responsive to said timing means for driving said scanning means to scan said stationary document;

settable control means for controlling the length of time said driving means is responsive to said timing means so that (l) with a first setting of said settable control means said scanning means scans substantially only. the length of said first sized document and is then returned to its starting position and (2) with a second setting thereof said scanning means scans substantially only the length of said second sized document and then is returned to its starting position; I 1 i second control means responsive tosaid second setting of said settable control means, said second controlrmeans being actuated when scanning of said second sized document is complete to decrease the time it takes for said timing means to complete its timing cycle so that the timing cyclefor said second sized document is shorter than that for said first sized document, said second control means comprising a second clutch, the input side of which is responsive to said source of rotative power and the output side of which is connected via a speed multiplying means to said main shaft, said speed multiplying means causing the rotational .speed imparted to said main shaft from the output side of said second clutch to be greater than that imparted thereto by said spring clutch where the difference in speed is absorbed in the spring of said spring clutch, said second clutch being actuated by a second control signal source which actuates said second clutch in response to said settable control means when said second sized document has been scanned to thereby accelerate the rotation of the output side of said spring clutch through its predetermined angle of rotation while said scanning means is being returned to said start position, said second clutch being deactuated approximately just before said output side has been rotated through said predetermined angle,

whereby the number of said second sized documents that may be copied per unit time is greater than that of said larger first sized documents.

2. Apparatus as in claim 1 where said second control means causes that portion of the second sized document timing cycle when the scanning means is returned to its said start position to be substantially the same as the corresponding portion of the first sized document timing cycle.

3. Apparatus as in claim 1 where said predetermined angle is 360.

4. Apparatus as in claim 1 where said drivingv means includes (a) a drive pulley rotatably mounted on a main shaft connected to said output side of the spring clutch, said pulley being connected to said scanning means, (b) a notched collar fixedly mounted on said main shaft, and (c) a pawl rotatably mounted on said pulley, said pawl releasably engaging said notched collar so that the rotation of said output side of said spring clutch is transmitted via said main shaft, said collar, said pawl and said pulley to said scanning means for effecting scanning of said stationary document.

5. Apparatus as in claim 4 where said settable control means comprises a lever which is fixedly positionable in (a) a first lever position so that said lever causes said pawl to be released from the notched collar when said first sized document has been scanned and (b) a second lever position so that said lever causes said pawl to be released from the notched collar when said second sized document has been scanned.

6. Apparatus for driving the illumination exposure system of a copying machine where the illumination exposure system includes means for scanning a stationary document in a first direction and returning the scanning means in the opposite direction to a start position after scanning has been completed, said apparatus comprising:

a spring clutch, the input side of which is connected to a source of rotative power and the output side of which is connected to a main shaft;

a first control signal source for actuating said spring clutch to connect the input and output sides thereof, said spring clutch including means for disconnecting said input and output sides thereof after said output side has been rotated through a predetermined angle;

a drive pulley rotatably mounted on said main shaft, said pulley being connected to said scanning means;

a notched collar fixedly mounted on said main shaft;

a pawl rotatably mounted on said pulley, said pawl releasably engaging said notched collar so that the rotation of said output side of said spring clutch is transmitted via said main shaft, said collar, said pawl and said pulley to said scanning means for effecting scanning of said stationary document;

a lever which is fixedly positionable in (a) a first lever position so that said lever causes said pawl to be released from the notched collar when a first sized document has been scanned and (b) a second lever position so that said lever causes said pawl to be released from the notched collar .when a second sized document has been scanned;

a second clutch, the input side of which is connected to said source to rotative power and the output side of which is connected via a gear train to said main shaft, said gear train causing the rotational speed imparted to said main shaft from the output side of.

said second clutch to be greater than that imparted thereto by said spring clutch where the difference in speed is absorbed in the spring of said spring clutch, said second clutch being actuated by a second control signal source which actuates said second clutch in response to said lever releasing said pawl from said notched collar when said second sized document has been scanned to thereby accelerate the rotation of the output said of said spring clutch through its said predetermined angle of rotasaid start position, said second clutch being de-' actuated approximately just before said output side has been rotated through said predetermined angle whereby the number of said second sized documents that may be copied per unit time is greater than that of said larger, first sized documents.

7. Apparatus for driving the illumination exposure system of a copying machine where the illumination exposure system includes means for scanning a stationary document in a first direction and means for returning the scanning means in the opposite direction to a start position after scanning has been completed, said apparatus comprising:

variable, cyclic timing means for determine (1) a first timing cycle required for said scanning means to scan a first sized document and for said scanning means to be returned to its start position and (2) a second timing cycle required for said scanning means to scan a second sized document smaller than said first sized document and for said scanning means to be returned to its start position, said timing means being responsive to a control signal for initiating each timing cycle to thereby initiate scanning by said scanning means and said timing means being non-responsive to further control signals until each timing cycle is complete, said variable cyclic timing means comprising (a) a spring clutch, the input side of which is connected to a source of rotative power and the output side of which is removably connected to said driving means and (b) a first control signal source for actuating said spring clutch to connect theinput and output sides thereof, said spring clutch including means for disconnecting said input and output sides thereof after said output side has been rotated through a predetermined angle;

driving means responsive to said timing means for driving said scanning means to scan said stationary document, said driving means including (a) a drive pulley rotatably mounted on a main shaft connected to said output side of the spring clutch, said pulley being connected to said scanning means, (b) a notched collar fixedly mounted on said main shaft, and (c) a pawl rotatably mounted on said pulley, said pawl releasably engaging said notched collar so that the rotation of said output side of said spring clutch is transmitted via said main shaft, said collar, said pawl and said pulley to said scanning means for effecting scanning of said stationary document;

settable control means for controlling the length of time said driving means is responsive to said timing means so that (1 )with a first setting of said settable control means said scanning means scans substantially only the length of said first sized document and is then returned to its starting position and (2) with a second setting thereof said scanning means scans substantially only the length of said second sized document and then returned to its starting position, said settable control means comprising a lever which is fixedly positionable in (a) a first lever position so that said lever causes said pawl to be released from the notched collar when said first sized document has been scanned and (b) a second lever position so that said lever causes said pawl to be released from the notched collar when said second sized document has been scanned,

second control means responsive to said second setting of said settable control means, said second control means being actuated when scanning of said second sized document is complete to decrease the time it takes for said timing means to complete its timing cycle so that the timing cycle for said second sized document is shorter than that for said first sized document, said second control means comprising a second clutch, the input side of which is connected to said source of rotative power and the output side of which is connected via a gear train to said main shaft, said gear train causing the rotational speed imparted to said main shaft from the output side of said second clutch to be greater than that imparted thereto by said spring 7 just before said output side has been rotated through said predetermined angle; whereby the number of said second sized documents that may be copied per unit time is greater than that of said larger first sized documents, 

1. Apparatus for driving the illumination exposure system of a copying machine where the illumination exposure system includes means for scanning a stationary document in a first direction and means for returning the scanning means in the opposite direction to a start position after scanning has been complEted, said apparatus comprising: variable, cyclic timing means for determining (1) a first timing cycle required for said scanning means to scan a first sized document and for said scanning means to be returned to its start position and (2) a second timing cycle required for said scanning means to scan a second sized document smaller than said first sized document and for said scanning means to be returned to its start position, said timing means being responsive to a control signal for initiating each timing cycle to thereby initiate scanning by said scanning means and said timing means being nonresponsive to further control signals until each timing cycle is complete, said variable cyclic timing means comprising (a) a spring cutch, the input side of which is connected to a source of rotative power and the output side of which is removably connected to said driving means via said main shaft, and (b) a first control source for actuating said spring clutch to connect the input and output sides thereof, said spring clutch including means for disconnecting said input and output sides thereof after said output side has been rotated through a predetermined angle; driving means mounted on a main shaft responsive to said timing means for driving said scanning means to scan said stationary document; settable control means for controlling the length of time said driving means is responsive to said timing means so that (1) with a first setting of said settable control means said scanning means scans substantially only the length of said first sized document and is then returned to its starting position and (2) with a second setting thereof said scanning means scans substantially only the length of said second sized document and then is returned to its starting position; second control means responsive to said second setting of said settable control means, said second control means being actuated when scanning of said second sized document is complete to decrease the time it takes for said timing means to complete its timing cycle so that the timing cycle for said second sized document is shorter than that for said first sized document, said second control means comprising a second clutch, the input side of which is responsive to said source of rotative power and the output side of which is connected via a speed multiplying means to said main shaft, said speed multiplying means causing the rotational speed imparted to said main shaft from the output side of said second clutch to be greater than that imparted thereto by said spring clutch where the difference in speed is absorbed in the spring of said spring clutch, said second clutch being actuated by a second control signal source which actuates said second clutch in response to said settable control means when said second sized document has been scanned to thereby accelerate the rotation of the output side of said spring clutch through its predetermined angle of rotation while said scanning means is being returned to said start position, said second clutch being deactuated approximately just before said output side has been rotated through said predetermined angle, whereby the number of said second sized documents that may be copied per unit time is greater than that of said larger first sized documents.
 2. Apparatus as in claim 1 where said second control means causes that portion of the second sized document timing cycle when the scanning means is returned to its said start position to be substantially the same as the corresponding portion of the first sized document timing cycle.
 3. Apparatus as in claim 1 where said predetermined angle is 360*.
 4. Apparatus as in claim 1 where said driving means includes (a) a drive pulley rotatably mounted on a main shaft connected to said output side of the spring clutch, said pulley being connected to said scanning means, (b) a notched collar fixedly mounted on said main shaft, and (c) a pawl rotatably mounted on said pulley, said pawl releasably engagIng said notched collar so that the rotation of said output side of said spring clutch is transmitted via said main shaft, said collar, said pawl and said pulley to said scanning means for effecting scanning of said stationary document.
 5. Apparatus as in claim 4 where said settable control means comprises a lever which is fixedly positionable in (a) a first lever position so that said lever causes said pawl to be released from the notched collar when said first sized document has been scanned and (b) a second lever position so that said lever causes said pawl to be released from the notched collar when said second sized document has been scanned.
 6. Apparatus for driving the illumination exposure system of a copying machine where the illumination exposure system includes means for scanning a stationary document in a first direction and returning the scanning means in the opposite direction to a start position after scanning has been completed, said apparatus comprising: a spring clutch, the input side of which is connected to a source of rotative power and the output side of which is connected to a main shaft; a first control signal source for actuating said spring clutch to connect the input and output sides thereof, said spring clutch including means for disconnecting said input and output sides thereof after said output side has been rotated through a predetermined angle; a drive pulley rotatably mounted on said main shaft, said pulley being connected to said scanning means; a notched collar fixedly mounted on said main shaft; a pawl rotatably mounted on said pulley, said pawl releasably engaging said notched collar so that the rotation of said output side of said spring clutch is transmitted via said main shaft, said collar, said pawl and said pulley to said scanning means for effecting scanning of said stationary document; a lever which is fixedly positionable in (a) a first lever position so that said lever causes said pawl to be released from the notched collar when a first sized document has been scanned and (b) a second lever position so that said lever causes said pawl to be released from the notched collar when a second sized document has been scanned; a second clutch, the input side of which is connected to said source to rotative power and the output side of which is connected via a gear train to said main shaft, said gear train causing the rotational speed imparted to said main shaft from the output side of said second clutch to be greater than that imparted thereto by said spring clutch where the difference in speed is absorbed in the spring of said spring clutch, said second clutch being actuated by a second control signal source which actuates said second clutch in response to said lever releasing said pawl from said notched collar when said second sized document has been scanned to thereby accelerate the rotation of the output said of said spring clutch through its said predetermined angle of rotation while said scanning means is being returned to said start position, said second clutch being de-actuated approximately just before said output side has been rotated through said predetermined angle whereby the number of said second sized documents that may be copied per unit time is greater than that of said larger, first sized documents.
 7. Apparatus for driving the illumination exposure system of a copying machine where the illumination exposure system includes means for scanning a stationary document in a first direction and means for returning the scanning means in the opposite direction to a start position after scanning has been completed, said apparatus comprising: variable, cyclic timing means for determine (1) a first timing cycle required for said scanning means to scan a first sized document and for said scanning means to be returned to its start position and (2) a second timing cycle required for said scanning means to scan a second sized document smaller than said first sized document aNd for said scanning means to be returned to its start position, said timing means being responsive to a control signal for initiating each timing cycle to thereby initiate scanning by said scanning means and said timing means being non-responsive to further control signals until each timing cycle is complete, said variable cyclic timing means comprising (a) a spring clutch, the input side of which is connected to a source of rotative power and the output side of which is removably connected to said driving means and (b) a first control signal source for actuating said spring clutch to connect the input and output sides thereof, said spring clutch including means for disconnecting said input and output sides thereof after said output side has been rotated through a predetermined angle; driving means responsive to said timing means for driving said scanning means to scan said stationary document, said driving means including (a) a drive pulley rotatably mounted on a main shaft connected to said output side of the spring clutch, said pulley being connected to said scanning means, (b) a notched collar fixedly mounted on said main shaft, and (c) a pawl rotatably mounted on said pulley, said pawl releasably engaging said notched collar so that the rotation of said output side of said spring clutch is transmitted via said main shaft, said collar, said pawl and said pulley to said scanning means for effecting scanning of said stationary document; settable control means for controlling the length of time said driving means is responsive to said timing means so that (1) with a first setting of said settable control means said scanning means scans substantially only the length of said first sized document and is then returned to its starting position and (2) with a second setting thereof said scanning means scans substantially only the length of said second sized document and then returned to its starting position, said settable control means comprising a lever which is fixedly positionable in (a) a first lever position so that said lever causes said pawl to be released from the notched collar when said first sized document has been scanned and (b) a second lever position so that said lever causes said pawl to be released from the notched collar when said second sized document has been scanned; second control means responsive to said second setting of said settable control means, said second control means being actuated when scanning of said second sized document is complete to decrease the time it takes for said timing means to complete its timing cycle so that the timing cycle for said second sized document is shorter than that for said first sized document, said second control means comprising a second clutch, the input side of which is connected to said source of rotative power and the output side of which is connected via a gear train to said main shaft, said gear train causing the rotational speed imparted to said main shaft from the output side of said second clutch to be greater than that imparted thereto by said spring clutch where the difference in speed is absorbed in the spring of said spring clutch, said second clutch being actuated by a second control signal source which actuates said second clutch in response to said lever releasing said pawl from said notched collar when said second sized document has been scanned to thereby accelerate the rotation of the output side of said spring clutch through its said predetermined angle or rotation while said scanning means is being returned to said start position, said second clutch being deactuated approximately just before said output side has been rotated through said predetermined angle; whereby the number of said second sized documents that may be copied per unit time is greater than that of said larger first sized documents. 